U.S. patent number 8,047,919 [Application Number 12/098,346] was granted by the patent office on 2011-11-01 for sideshaft with interconnecting fuse.
This patent grant is currently assigned to GKN Driveline North America, Inc.. Invention is credited to Tony N Arden, Samuel J Oram.
United States Patent |
8,047,919 |
Arden , et al. |
November 1, 2011 |
Sideshaft with interconnecting fuse
Abstract
An automotive shaft assembly is provided including a first
barshaft having a first connection end and a second barshaft having
a second connection end. A connection tube rotationally engages the
first connection to the second connection end and includes a shear
diameter configured to experience shear failure in the presence of
an overload torque such that the first connection end is
rotationally disengaged the said second connection end.
Inventors: |
Arden; Tony N (Davisburg,
MI), Oram; Samuel J (Rochester Hills, MI) |
Assignee: |
GKN Driveline North America,
Inc. (Auburn Hills, MI)
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Family
ID: |
41133777 |
Appl.
No.: |
12/098,346 |
Filed: |
April 4, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20090253521 A1 |
Oct 8, 2009 |
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Current U.S.
Class: |
464/32; 72/713;
403/359.1; 403/2 |
Current CPC
Class: |
F16D
9/06 (20130101); F16D 1/02 (20130101); F16D
1/10 (20130101); Y10T 403/11 (20150115); Y10T
403/7026 (20150115); F16D 2001/103 (20130101); Y10S
72/713 (20130101) |
Current International
Class: |
F16D
9/08 (20060101) |
Field of
Search: |
;464/32,170,182
;403/2,359.1 ;72/370.25,713 ;29/888 ;285/4 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Binda; Gregory
Attorney, Agent or Firm: Brumbaugh; Jennifer M. Nylander;
Mick A. Rader, Fishman & Grauer PLLC
Claims
What is claimed is:
1. An automotive shaft assembly comprising: a first barshaft having
a first connection end; a second barshaft having a second
connection end; and a connection tube rotationally engaging said
first connection to said second connection end, said connection
tube including a shear diameter configured to experience shear
failure in the presence of an overload torque such that said first
connection end is rotationally disengaged from said second
connection end, wherein said connection tube is secured
longitudinally directly to an outer surface of said first and
second barshafts; wherein said first connection end comprises first
external splines; said second connection end comprises second
external splines; and said connection tube comprises connection
internal splines engaging said first external splines and said
second external splines.
2. The automotive shaft assembly according to claim 1 wherein: said
connection tube comprises: a first portion comprising a first tube
main diameter; and a second portion comprising a second tube main
diameter, wherein said shear diameter is positioned between said
first portion and said second portion.
3. The automotive shaft assembly according to claim 1 wherein said
connection tube comprises: a plurality of circumferentially spaced
engagement bores; and a plurality of engagement members positioned
in said engagement bores, said engagement members securing said
connection tube to said first barshaft and said second
barshaft.
4. The automotive shaft assembly according to claim 3, wherein:
said first barshaft includes a first channel; and said second
barshaft includes a second channel, said first and second channels
configured to receive said engagement members.
5. The automotive shaft assembly according to claim 1, further
comprising: a protection sleeve surrounding said connection tube,
said protection sleeve retaining said first barshaft and said
second barshaft in approximate axially parallel orientation when
said first barshaft and said second barshaft are rotationally
disengaged.
6. The automotive shaft assembly according to claim 5, wherein said
protection sleeve further comprises a plurality of
circumferentially distributed inspection ports.
7. The automotive shaft assembly according to claim 5, wherein said
connection tube comprises: a plurality of circumferentially spaced
engagement bores; and a plurality of engagement screws positioned
in said engagement bores, said engagement screws securing said
connection tube to said first barshaft and said second barshaft;
wherein said plurality of engagement screws restrain axial movement
of said protection sleeve, said plurality of engagement screws
leaving said protection sleeve rotationally free.
8. An automotive driveline assembly comprising: a differential
assembly; and at least one sideshaft assembly in communication with
said differential assembly, said sideshaft assembly comprising: a
first barshaft having a first channel configured to receive at
least one engagement screw and a first connection end; a second
barshaft having a second channel configured to receive at least one
engagement screw and a second connection end; and a connection tube
rotationally engaging said first connection to said second
connection end, said connection tube including a shear feature
configured to experience shear failure in the presence of a design
torque such that said first connection end is rotationally
disengaged from said second connection end, wherein said connection
tube includes at least one engagement bore spaced about the
circumference of the connection tube, said engagement bore being
configured to receive the at least one engagement screw and said
engagement screw securing said connection tube to said first
barshaft and said second barshaft.
9. An automotive driveline assembly as described in claim 8,
wherein said shear feature comprises a shear diameter, said
connection tube comprising: a first portion comprising a first tube
main diameter; and a second portion comprising a second tube main
diameter, wherein said shear diameter is positioned between said
first portion and said second portion.
10. The automotive driveline assembly according to claim 8 wherein:
said first connection end comprises first external splines; said
second connection end comprises second external splines; and said
connection tube comprises connection internal splines engaging said
first external splines and said second external splines.
11. The automotive driveline assembly according to claim 8, further
comprising: a protection sleeve retaining said first barshaft and
said second barshaft in approximate axially parallel orientation
when said first barshaft and said second barshaft are rotationally
disengaged.
12. The automotive driveline assembly according to claim 11,
wherein said protection sleeve further comprises a plurality of
circumferentially distributed inspection ports.
13. The automotive driveline assembly according to claim 11,
wherein: said at least one engagement bore is a plurality of
engagement bores spaced about the circumference of the connection
tube; said at least one engagement screw is a plurality of
engagement screws positioned in said engagement bores, said
engagement screws securing said connection tube to said first
barshaft and said second barshaft; and said plurality of engagement
screws restrain axial movement of said protection sleeve.
14. A method of protecting an automotive shaft assembly from
overload torque comprising: utilizing a first barshaft having a
first connection end and a second barshaft having a second
connection end; rotationally connecting said first connection end
to said second connection end using a connection tube, said
connection tube is directly secured longitudinally to an outer
surface of the first barshaft and the second barshaft, said
connection tube including a shear feature configured to experience
shear failure in the presence of the overload torque such that said
first connection end is rotationally disengaged from said second
connection end; and maintaining said first barshaft and said second
barshaft in approximate axially parallel orientation when said
first barshaft and said second barshaft are rotationally disengaged
using a protection sleeve surrounding said connection tube.
15. A method according to claim 14, wherein said protection sleeve
includes a plurality of circumferentially distributed inspection
ports positioned such that said shear feature may be inspected
after assembly.
16. A method according to claim 14, wherein said shear feature
comprises a shear diameter.
Description
TECHNICAL FIELD
The present invention relates generally to motor vehicle shafts,
and more particularly concerns a interconnecting shaft with torque
overload protection.
BACKGROUND
Connection shafts and drive units are common components in
vehicles. The drive unit typically has an output shaft or an input
shaft for receiving a joint. Typically, the drive unit is an axle,
transfer case, transmission, power take-off unit or other torque
device, all of which are common components in automotive vehicles.
Typically, one or more joints are assembled to the shaft to form a
propeller or drive shaft assembly. It is the propeller shaft
assembly which is connected, for instance, at one end to the output
shaft of a transmission and, at the other end, to the input shaft
of a differential. The shaft is solid or tubular with ends adapted
to attach the shaft to an inner race of the joint thereby allowing
an outer race connection to a drive unit. The inner race of the
joint is typically press-fit, splined, or pinned to the shaft
making the outer race of the joint available to be bolted or
press-fit to a hub connector, flange or stubshaft of the particular
drive unit. At the other end of the propeller shaft, the same
typical or traditional connection is made to a second drive unit
when connecting the shaft between the two drive units. Optionally,
the joint may be coupled to a shaft for torque transfer utilizing a
direct torque flow connection.
In many off road vehicle environments considerable torque is
applied through both the various shafts as well as their respective
joints. All Terrain Vehicles and Utility Vehicles often have
drivelines that are subject to unusually high torque values during
unusual or extreme events. These events often arise when the
vehicle lands after jumping off irregular terrain. The impact upon
landing generates considerable torque in the drivelines. This
torque is typically subsequently imparted into the individual
components of the constant velocity joint. When the torque imparted
into the CV joint components exceeds design considerations, the
components can experience failure. A common design response to
these extreme conditions has been to increase the size of the CV
joint components in order to increase their maximum torque
weathering capacity.
In addition to the extreme conditions, designers are utilizing
higher capacity engines in vehicle designs. These higher capacity
engines increase the power passed through the drivelines and
therefore increase the overload torques experienced during extreme
conditions. Existing methods of compensation require continued
upsizing of the drivelines in order to accommodate the increased
power and resulting increased overload torques. Continued upsizing,
however, results in increases in mass of the driveline components
with subsequent mass increases to the vehicle itself. Upsizing,
therefore, poses undesirable restrictions on vehicle designers.
It would be advantageous to have a torque overload protection
feature incorporated into the driveline such that component
upsizing, and its negative consequences, could be avoided or
minimized.
SUMMARY OF THE INVENTION
An automotive shaft assembly is provided including a first barshaft
having a first connection end and a second barshaft having a second
connection end. A connection tube rotationally engages the first
connection to the second connection end and includes a shear
diameter configured to experience shear failure in the presence of
an overload torque such that the first connection end is
rotationally disengaged from said second connection end.
The present invention has advantages by providing a torque overload
protection without requiring an increase in component size. The
present invention itself, together with further intended
advantages, will be best understood by reference to the following
detailed description and taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of this invention, reference
should now be made to the embodiments illustrated in greater detail
in the accompanying drawings and described below by way of examples
of the invention.
FIG. 1 shows a plan view of an exemplary drive system for a typical
4-wheel drive vehicle wherein the present invention may be used to
advantage.
FIG. 2 shows a cross-sectional illustration of an automotive shaft
assembly in accordance with the present invention, the automotive
shaft assembly illustrated in a rotationally engaged fashion.
FIG. 3 is an exploded view illustration of the automotive shaft
assembly illustrated in FIG. 2.
FIG. 4 is a cross-sectional illustration of the automotive shaft
assembly illustrated in FIG. 2, the automotive shaft assembly
illustrated in a rotationally disengaged fashion.
DETAILED DESCRIPTION
In the following description, various operating parameters and
components are described for one or more constructed embodiments.
These specific parameters and components are included as examples
and are not meant to be limiting.
While the invention is described with respect to a automotive shaft
assembly with overload torque protection for use in an all-terrain
vehicle, the following apparatus is capable of being adapted for
various purposes including automotive vehicles drive axles, motor
systems that use a propeller shaft, or other vehicles and
non-vehicle applications which require shaft assemblies for torque
transmission.
An exemplary drive system 12 for a typical 4-wheel drive vehicle is
shown in FIG. 1. While a 4-wheel drive system is shown and
described, the concepts herein presented could apply to a single
drive unit system or multiple drive unit system, including rear
wheel drive only vehicles, front wheel drive only vehicles, all
wheel drive vehicles, and four wheel drive vehicles. In this
example, the drive system 12 includes an engine 14 that is
connected to a transmission 16 and a power take-off unit 18. A
front differential 20 has a right hand side half shaft 22 and left
hand side half shaft 24 each of which are connected to a wheel and
deliver power to the wheels. On both ends of the right hand side
half shaft 22 and left hand side half shaft 24 are constant
velocity joints 10. A propeller shaft 26 connects the front
differential 20 to a rear differential 28 wherein the rear
differential 28 includes a rear right hand side shaft 30 and a rear
left hand side shaft 32, each of which ends with a wheel on one end
thereof. Constant velocity joints 10 are located on both ends of
the half shafts 30, 32 that connect to the wheels and the rear
differential 28. The propeller shaft 26, shown in FIG. 1, is a
three-piece propeller shaft that includes a plurality of cardan
joints 34 and one high-speed constant velocity joint 10. The
propeller shaft 26 includes interconnecting shafts 23, 25, 27. The
constant velocity joints 10 transmit power to the wheels through
the propeller shaft 26 even if the wheels or the propeller shaft 26
have changed angles due to steering, raising or lowering of the
suspension of the vehicle. The constant velocity joints 10 may be
any of the standard types known, such as a plunging tripod, a cross
groove joint, a fixed ball joint, a fixed tripod joint, or a double
offset joint, all of which are commonly known terms in the art for
different varieties of constant velocity joints 10. The constant
velocity joints 10 allow for transmission of constant velocities at
angles typically encountered in the off road travel of all-terrain
vehicles in both the half shafts, interconnecting shafts and
propeller shafts of these vehicles. Optionally, each cardan joint
34 may be replaced with any other suitable type of joint, including
constant velocity joint types. The constant velocity universal
joint with torque overload protection may be utilized to advantage
for any of the above mentioned joint locations.
The shafts 22, 23, 24, 25, 27, 30, 32 may be solid or tubular with
ends adapted to attach each shaft to an inner race or an outer race
of a joint, thereby allowing the outer race or inner race to be
connected to a hub connector 36, a flange 38 or stubshaft 40 of
each drive unit, as appropriate, for the particular application.
Thus, any of the traditional shafts identified in FIG. 1 may be
automotive shaft assemblies with torque overload protection in
accordance with the present invention (FIG. 2).
Referring now to FIGS. 2 and 3, which are illustrations of an
automotive shaft assembly with torque overload protection 50 in
accordance with the present invention. It is contemplated that the
automotive shaft assembly 50 may comprise an automotive sideshaft,
a driveshaft, or even an additional assembly tied in thereto. The
automotive shaft assembly 50 is comprised of a first barshaft 52
having a first connection end 54 and a second barshaft 56 having a
second connection end 58. It should be understood that the first
and second barshafts 52,56 may comprise a two piece sideshaft 30,32
or other shaft assembly or may simply comprise a component to be
mounted inline with these shafts. The two barshafts 52, 56 are
placed in rotational engagement by way of a connection tube 60.
This is preferably accomplished by the connection tube 60
rotationally engaging the first connection end 54 and the second
connection end 58 such that the barshafts 52,56 rotate in
unison.
Although a variety of configurations for such rotational engagement
are contemplated, one embodiment contemplates the use of a first
plurality of external splines 62 formed on the first connection end
54 and a second plurality of external splines 64 formed on the
second connection end 58. A plurality of connection internal
splines 66 formed on an inner surface 68 of the connection tube 60
are configured to engage the external splines 62,64 when inserted
into the connection tube 60 such that the first barshaft 52 becomes
in rotational unity with the second barshaft 56. The connection
tube 60 may be further secured through the use of a plurality of
circumferentially spaced engagement bores 70. A plurality of
engagement screws 72 such as grub screws may be positioned within
the engagement bores 70 and tightened down to further secure the
connection tube 60 to the barshafts 52,56. As the splines 62,64,66
work to secure rotational engagement, the engagement screws 72 may
in one embodiment be used to primarily secure axial engagement. In
such an embodiment, the barshafts 52,56 may include a first channel
74 and a second channel 76 respectively to engage the screws 72 for
axial fixation.
The present invention provides torque overload protection by way of
a shear feature 78 formed into the connection tube 60. The shear
feature 78 is configured to experience shear failure 98 during
torque overload such that the first barshaft 52 becomes
rotationally disengaged from the second barshaft 56 (see FIG. 4).
In one embodiment, it is contemplated that the shear feature 78 is
comprised of a shear diameter 80, namely a reduced diameter that
when taken in combination with the material properties of the
connection tube 60 will shear fracture at a given overload torque.
In this embodiment, the connection tube 60 is preferably comprised
of a first portion 82 having a first tube main diameter 84 and a
second portion 86 having a second tube main diameter 88. The shear
diameter 80 is preferably positioned between these portions 82,86
and is coincident with a mating region 90 of the first barshaft 52
and the second barshaft 56.
It is contemplated that when the shear feature 78 fails due to
overload torque, the barshafts 52,56 will become rotationally
independent. It may be desirable, however, to retain their general
axially parallel orientation such that the maintain their general
position and do not interfere with other automotive structures. As
such the present invention contemplates the use of a protection
sleeve 92 to maintain the axial orientation of the barshafts 52,56
during disengagement. In one embodiment, it is contemplated that
the protection sleeve 92 surround the connection tube 60 without
providing rotational engagement to the barshafts 52,56. In one
embodiment, it is contemplated that the engagement screws 72 extend
above the connection tube outer surface 94 after installation to
secure the axial orientation of the protection sleeve 92. This
insures the protection sleeve 92 remains properly orientated
axially even after disengagement.
It is contemplated that the protection sleeve 92 may include a
plurality of circumferentially distributed inspection ports 96
preferably positioned to coincide with the shear feature 78 after
installation. In this way, the status of the connection tube 60
(engaged or sheared and disengaged) can be easily identified even
after installation. This allows for simple identification of
failure to facilitate maintenance. An advantage of the present
invention is that when a vehicle experiences undesirable overload
torque, only the connection tube 60 experiences failure and damage
is not transferred to expensive driveline parts. The connection
tube 60, and protection sleeve 92, may then be easily removed and
replaced.
From the foregoing, it can be seen that there has been brought to
the art a new and improved automotive shaft assembly with torque
overload protection. While the invention has been described in
connection with one or more embodiments, it should be understood
that the invention is not limited to those embodiments. On the
contrary, the invention covers all alternatives, modifications, and
equivalents as may be included within the spirit and scope of the
appended claims.
* * * * *